Probiotics are microbial-based dietary adjuvants that beneficially affect the host physiology by modulating mucosal and systemic immunity, as well as improving intestinal function and microbial balance in the intestinal tract (Naidu, A. S., et al. (1999), Probiotic spectra of lactic acid bacteria (LAB). Crit. Rev. Food Sci. Nutr. 39:3-126). Various nutritional and therapeutic effects have been ascribed to these probiotics including: modulating immune response, lowering serum cholesterol concentrations, improving lactose intolerance symptoms, increasing resistance to infectious intestinal diseases, decreasing diarrhea duration, reducing blood pressure, and helping to prevent colon cancer.
However, in order to exert these beneficial effects on the host, probiotics must retain their viability and reach the large intestine in large quantities (Favaro-Trindade, C. S., et al. (2002), J Microencapsulation 19(4): 485-494)). Effective probiotic bacteria should be able to survive gastric conditions and colonize the intestine, at least temporarily, by adhering to the intestinal epithelia (Conway, P. (1996), Selection criteria for probiotic microorganisms. Asia Pacific J. Clin. Nutr 5:10-14).
Lactic acid bacteria or Lactobacilli are the most commonly used probiotic for incorporation into dairy products such as yogurts, fermented milks and kefirs, and their use is continually becoming more widespread. For example, they are now added in dietary supplement forms, such as powders, capsules and tablets. Bifidobacteria and Streptococci are also commonly used probiotic microorganisms. Lactic acid bacilli generally require an effective delivery system that retains probio-functional activities (i.e., gut adhesion/retention, production of bacteriocins/enzymes) after their revival (Salminen, S., et al. (1996), Clinical uses of probiotics for stabilizing the gut mucosal barrier: successful strains and future challenges. Antonie Van Leeuwenhoek 70:347-3581). Furthermore, in addition to increasing in vivo viability and gastrointestinal tract life span, prolonged shelf life at room temperature remains a challenge in the manufacture of effective commercial products. Though freeze-drying of the probiotic bacteria has been shown to be an effective process for preservation and delivery of probiotics, several physico-chemical factors such as humidity, aeration (oxygen availability), processing (i.e., agitation), and temperature could compromise the cell viability and, accordingly, the shelf life.
The stability, viability (i.e., viable microbial content) and quality of products containing probiotic bacteria have been problematic, as evidenced by scientific literature. In one study regarding yogurts, the experiments yielded evidence that 3 of 6 products tested contained no traces of live microorganisms and two contained only low concentrations. Shah (2000) Journal of Dairy Science, 83(4): 894-907. Similar reports have issued with regard to products containing probiotic bacteria distributed in solid dosage forms such as powders, capsules and tablets. The predominant challenges to stability of probiotic bacteria are water activity, physical stress of processing and temperature. It has also been challenging to apply protective measures, such as coatings, that will release the probiotic bacteria at the appropriate delivery site in the body and allow the probiotic to colonize. The appropriate delivery and colonization of the coated probiotic bacteria has recently been confirmed in a newly published study (Del Piano, M., et al. (2010), Evaluation of the intestinal colonization by microencapsulated probiotic bacteria in comparison to the same uncoated strains, Journal of Clinical Gastroenterology, 44 Supp. 1: S42-6.)
Oil suspensions have been utilized to increase the viability and shelf life of probiotics. For example, U.S. Patent Application Publication No. 2004/0223956 discloses a composition containing probiotic bacteria suspended in an edible oil and, optionally, encapsulated in a two piece hard shell capsule.
In addition, those in the art have tried using probiotic microspheres to enhance viability and shelf life. For example, U.S. Patent Application Publication No. 2005/0266069 discloses probiotic formulations containing probiotic microspheres having a core of a probiotic bacteria and a cellulosic excipient coated with coating agents and plasticizers.
Experience has long shown that pharmaceuticals or other items for human or animal consumption may be safely and conveniently packaged in a hard or soft gelatin (softgel) shell.
Filled one-piece soft capsules or softgels have been widely known and used for many years and for a variety of purposes and are capable of retaining a liquid fill material. Most frequently, softgels are used to enclose or contain consumable materials such as vitamins, minerals, fruits and botanical extracts and pharmaceuticals in a liquid vehicle or carrier.
Encapsulation within a soft capsule of a solution or dispersion of a nutritional or pharmaceutical agent in a liquid carrier offers many advantages over other dosage forms, such as compressed, coated or uncoated solid tablets, or bulk liquid preparations. Encapsulation of a solution or dispersion permits accurate delivery of a unit dose. Soft capsules provide a dosage form that is easy to swallow and need not be flavored, a good oxygen barrier (i.e., low oxygen permeability through the capsule shell), and tamper protection. Soft capsules are also more easily transported than food products and liquids, such as yogurt and milk.
Probiotics are commercially available in seamless or soft gelatin capsules. Bifa-15™ (Eden Foods, Inc., Clinton, Mich.) is a seamless microencapsulation delivery system for Bifidobacteria, claiming to contain three billion bacteria. The capsules are admixed with oligosaccharides, sweeteners and flavors and presented in individually wrapped, single dose aluminum tubes. The contents are poured into the mouth with the proviso that capsules be swallowed whole and not chewed. Ultra-Dophilus™ (Nature's Plus, Melville, N.Y.) is a conventional-sized soft gelatin capsule containing two billion viable freeze-dried L. acidophilus. Probiotocs12Plus™ are soft capsules containing 12 strains of lactic acid bacteria with the aim of a 900 colony forming units potency at the time of manufacture, and no refrigeration required. While each product declares a viability at the time of manufacture, there is no guarantee that the label claim will be met following storage at room temperature, e.g., 22-25° C., in the future. Similar problems in maintaining viability in probiotics contained in gelatin capsules are also evident from patent literature.
The softgels in the art containing probiotic bacteria have been largely unsuccessful. Softgel formulations have not maintained the desired viability, often measured in colony forming units (CFU), for the designed shelf life of the product (typically 2 years), especially at room temperature. The vitality of the probiotic bacteria has tended to decline too rapidly to be successful. This is believed to be due in part to the high water activity Aw (free water) in the softgel environment. This Aw gradient is linked to the softgel production process itself (particularly the encapsulation phase). During this phase, some of the water present in the capsule shell migrates to the formulation within the shell, where it is retained in a free form. In the case of a formulation containing probiotic bacteria, free water activates the probiotic bacteria causing them to perish shortly thereafter.
In addition, the manufacturing process of a softgel challenges the stability of a probiotic bacteria within the softgel as it may stress the probiotic bacteria, even if coated, thereby lessening the viability and stability.
Therefore, there is a need for providing increased viability and stability of probiotic bacteria in products upon prolonged storage at room temperature, as this continues to challenge the industry. In particular, there is a need for a stable softgel capsule containing probiotic bacteria having enhanced viability and shelf life.